Participants were tested individually in their classrooms. They were told that their responses were anonymous. Given the
number of respondents with low educational ability, we used short and simple measures. Sensation seeking was measured
using a 2-item scale (e.g., “I like to do risky things, even if they are dangerous”; Slater et al., 2003; Cronbach a ¼ .83). Trait
aggressiveness was measured using the 9-item (e.g., “I fight more often than most other people do”) physical aggression
subscale of the Aggression Questionnaire (Buss & Perry, 1992; Cronbach a ¼ .76). Items on both scales were rated using
a 7-point scale (1 ¼ disagree completely to 7 ¼ agree completely).
Participants were equally distributed across the three levels: 33.4% were from VMBO schools, 33.0% were from HAVO
schools, and 33.6% were from VWO schools.